Abstract: XY female can be created by genetic manipulation of the gonadal soma derived factor (gsdf), through transgenic over-ex-pression or targeted disruption ofgsdfin medaka (Oryziaslatipes), however, the bio-function and target genes ofgsdfare still unclear. We used Label Free proteomics combined with Mass Spectrometry (MS) to quantitatively compare the protein expression profiles of nor-mal XX ovaries, XY testis, andgsdf-deficient XY ovaries. Result showed that the protein level of ovarian isoform (42Sp50) of eukary-otic translation elongation factor 1a (eEF1a) was significantly enhanced ingsdfdepletion ovaries, in contrast to the normal male or fe-male. The transcripts of42Sp50were also significantly enriched in XYgsdfdeficiency ovaries by real-time PCR quantitative analysis, in contrast to less expression in normal XX ovaries or rare in XY testis. The amino acid sequence of medaka eEF1a was highly homolo-gous to human EEF1A, but significantly different from medaka42sp50in the region of amino-acyl binding pocket. The expression ofeEF1aincluding42Sp50was examined in gonads during sexual differentiation, and mature gonads of normal female, male andgsdfde-pletion ovary by immunofluorescence using anti-human EEF1A antibody. Evidence of normal XX distinct fromgsdf-deficient XY oo-cytes by dual-color immunofluorescent analysis provides a new clue for the mechanism of vertebrate gametogenesis.

Key words: gsdf;eEF1a;42Sp50, oogenesis, medaka